The National Data Protection Commission said it was fining Google for a "lack of transparency, inadequate information and lack of valid consent" on ad personalization, arguing that users were "not sufficiently informed" about the details in the agreement.

"The amount decided, and the publicity of the fine, are justified by the severity of the infringements observed regarding the essential principles of the GDPR: transparency, information and consent," the group said in a statement, referring to the General Data Protection Regulation (GDPR).

The new rules, which were implemented in May, forced large tech companies like Google to overhaul their user privacy policies. The European Union-based rules require companies to give full disclosure about what they do with the digital data they collect and offer their users more control over their information.

The watchdog group argued that Google violated the new privacy rules in two key areas.

"Users are not able to fully understand the extent of the processing operations carried out by GOOGLE. But the processing operations are particularly massive and intrusive because of the number of services offered (about twenty), the amount and the nature of the data processed and combined," the group said.

They added that while Google "states that it obtains the user’s consent to process data for ads personalization purposes. However, the restricted committee considers that the consent is not validly obtained."